Study On Resistant Mechanism Of P.neumoniae To β-lactams In Pediatric

Antibiotic is one of the best achievements in medicine which improve human health level and ensure people life.However with the abuse of antibiotic,more and more drug-resistance bacteria created and drug induced sufferings occurred frequently especially for children.As to the beta-lactam antibiotics with powerful antibacterial activity, broad antimicrobial spectrum and low toxicity, especially the third generation cephalosporins, they play an important part in the treatment of Gram-negative bacteria infection and have been the most popular antibiotics in clinic. However, with the widespread use of the numerous new beta-lactam antibiotics, the resistant strains have appeared increasingly resently. One of the most important reason is that more and more new kinds ofβ-lactamases called extended-spectrumβ-lactamases(ESBLs) appeared under the antibiotics selective pressure. ESBLs have spread substrates, and have the ability to hydrolyse penicillins, cephalosporins and monobactams. Since first described in 1983, ESBLs have been reported at almost everywhere in the world. There are many reports about the breaks of nosocomial infection induced by ESBLs-producing bateria.Respiratory infection is common and frequently encountered disease for children and it is offen treated with many kinds of antibiotics. We conduct an epidemiological survey and analysis about the antibiotic use in hospitalized child of hospital respiratory department so as to identify the reasons of antibiotic irrationalitical use in Jilin.We also study the isolating rate and antibiotic resistance of P.neumoniae which is isolated from respirator infected children and analysis them with Whonet in order to identify the differences of isolating rate and antibiotic resistance. We draw the trendgraph of antibiotic resistance analysis genetic mechanism of antibiotic resistance of P.neumoniae for the study of pediatric bacteial antibiotic resistance.A total of 135 clinical isolates of K.pneumoniae were collected. Antibiotics susceptibilities were determined by K-B method. ESBLs-producing isolates were detected by phenotypic screening and confirmatory test according to the methods recommended by CLSI/NCCLS. PCR amplification and nucleotide sequencing were used to analyze the genotypes of ESBLs. The results showed that 76 isolates were identified as ESBLs -producing strains by phenotypic confirmatory test and the incidence was 56.3%. Detected rate of K.pneumoniae was 33.3%, 58.5%, 68.9% respectively from 2004 to 2006 and much higher than other reporter abraod. The strains ESBLs -producing were isolated from sputum specimens collected from resparatory tract in pedartric and ICU ward. As a result of the patients diseases and age, the wide spectrum cephalosporin were used so greatly that ESBLs-producing isolates appeared increasingy while antibiotica as selective pressure.Frequency distribution showed that second generation cephalosporin and third generation cephalosporin were mainly used. The use of ZTP is increasing in these three years. This indicates that antibiotic resistance has provoked reconcentration in this area. The resistance rate of K.pneumoniae clinical isolates against the first, second and third generation cephalosporins up to 100%. And resistance rate to CRO, CFX, AZT and aminoglycosides were all more than before. The ESBLs-producing isolates were more resistant to most antimicrobials than non-ESBLs-producers. All were concerned about the fact that all isolates ESBLs-producing harboured the plasmid with resistant gene to aminoglycosides, quinolones, chloramphenicol. The clinical patiets infected by ESBLs-producing bacteria were treated with antimicrobial such as cephamycin,β-lactams/inhibitor or imipenem according to drug susceptibility test.Sequencing analysis showed that the most frequently identified ESBLs genes in this group were blaTEM-1, blaSHV-12, blaSHV-2a blaCTX-M-2.The results ofβ-lactamases genotyping show that 26 isolates carried blaTEM(34.2%),9 isolates carried blaSHV(11.8%), 4 isolates carried blaCTX-M-2(5.3%). Among phenotype positive strains, there coexisted with many different ESBLs genes.Bacteria face strong selection pressure from antibiotic use could cause the antibiotic resistance strains are increacing. The irrational use of antibiotic causes drug resistant strains increasing, disadvantages for treating and is harm to growth and development of children. So some metods should be taken. First of all, antibiotic use should be according to susceptibility test, or base on the statistic results of pathogenic bacteria in its own area. Secondly, efficient and cheap antibiotics should be chosen by any chances. Thirdly, antibiotics conbined use should be according to synergetic principal.Last, we should not replace antibiotics frequently without any identical indications.We investigated the distribution and characterization and infection condition of K.pneumoniae ESBLs-producing to survey on their resistance property, and to reveal the molecular epidemiological characteristics, inquiring into the molecular mechanisms of the emergence and dissemination of their multiple resistance. The results provided significant theory to control and prevent strains ESBLs-producing.